植物微生物燃料電池運行於鎘污染土壤之復育及產電效能之研究

Abstract

植物微生物燃料電池(Plant microbial fuel cell, PMFC)作為一種新興的綠色能源，具有透過植物將太陽能轉換為電力之能力，是具備環境友善、碳中和、成本低廉等新興科技，除此之外，植物微生物燃料電池尚具有去除汙染物之能力，不僅能有效降低廢水或是土壤中之化學需氧量，甚至能夠還原部分重金屬來達到去除水體或是土壤中之重金屬汙染的目的。 植物微生物燃料電池是經由微生物燃料電池衍伸而來，由埋在土壤的陽極、植物、放在水表面之陰極及外接電路組成，透過土壤取代一般微生物燃料電池內的離子交換膜，使植物微生物燃料電池可分為深層土壤中之厭氧陽極槽及與空氣接觸之耗氧陰極槽。本研究以植物微生物燃料電池去除土壤中之鎘(Cd)汙染作為研究目標， 以直徑15 cm、厚度0.4 cm之圓形碳氈作為電極，並使用香蒲(Typha orientalis)及野生稻(Oryza rufipo gon)作為PMFC系統之研究對象，同時也根據環保署所公布之土壤汙染管制標準(20 m g/k g)及土壤汙染監測標準(10 m g/k g)來配置不同濃度的鎘汙染土壤。結果顯示野生稻PMFC系統比起香蒲PMFC有更高之產電能力，野生稻組之PMFC產生之最高電壓來到0.64 V，而香蒲組之PMFC所能產生之最高電壓僅到0.43 V，平均之電壓產生也是野生稻組略勝一籌，可以得到野生稻是較適合用於PMFC系統產電之植物。在土壤中鎘的去除率研究中，香蒲組PMFC在高濃度(20 m g/k g)的鎘汙染土壤中達到了30 %的去除率，而在相同之條件下野生稻僅有14 %的去除率，若以處理土壤中鎘汙染為目標，香蒲PMFC可以達到較優良的去除效果。植物微生物燃料電池是近幾年來新興之研究，利用植生復育法結合微生物燃料電池去除土壤中重金屬，具有去除汙染物並同時產能之優勢，將來實際應用在汙染場址的重金屬去除上有良好的潛力。

Plant microbial fuel cell (PMFC), as an new green energy source, has the ability to convert solar energy into electricity through plants. PMFC have received increasing attention due to it’s many advantages,s such as eco-friendly, carbon neutrality, and low cost. In addition, PMFCs still have the ability to remove pollutants, not only can effectively reduce the COD, but also reduce some heavy metals at the cathode in wastewater or contaminated soil. The PMFC consists of an anode buried in the soil, a plants and a cathode placed on the surface of the water. The soil replaces the ion exchange membrane in the general MFC which can help anode to stand anaerobic environment for the electrochemically active bacteria. In this study, the removal of cadmium (Cd) from soil by PMFCs was studied. Two of 15 cm diameter and a 0.4 cm thickness circular carbon felts were used as electrodes, and Typha orientalis and Oryza rufipogon were used as a research plants of the PMFCs, Different concentrations of Cd-contaminated soil were also configured according to the soil pollution control standards (20 mg/kg) and soil pollution monitoring standards (10 mg/kg) which were published by the Environmental Protection Administration in Taiwan. The results show that the highest voltage generated by the the Oryza rufipogon PMFC comes to 0.64 V, while the highest voltage that the Typha orientalis PMFC can produce is only 0.43 V., The average voltage generation from the Oryza rufipogon PMFC is also slightly better than that of the Oryza rufipogon PMFC. It shows that Typha orientalis is more suitable for electricity production in the PMFC. However, in the study of the removal rate of Cd in soil, the Typha orientalis PMFC achieved a Cd removal rate of 30% in the high Cd contaminated soil (20 mg/kg), while the removal rate of Oryza rufipogon PMFC was only 14% under the same conditions. If the target is treating Cd in contaminated soil, Typha orientalis PMFC can achieve better removal rate. PMFC is an emerging research in recent years. The use of phytoremediation combined with MFCs to remove heavy metals from soils has the advantage of removing pollutants and producing electricity simultaneously. In the future, maybe it will be a perfect way to recover heavy metals from the contaminated sites.